(International Consortium of Investigative Journalists (ICIJ))
Norway their tax authorities don't post that information in a searchable online database.
The spirit of transparency that has propelled Britain's top politicians to release their tax returns is already a fact of life in Norway, where the annual financial details of every taxpayer are published online in a searchable database.
With the recent spotlight on the opaque world of offshore finance, some are looking to Norway as an example to follow at least for public figures.
"We believe transparency contributes to legitimacy and trust in the tax system," said Mariken Holter, a spokeswoman for the Norwegian Tax Administration. Tax payments are also considered public information in Finland and Sweden, which like Norway are consistently ranked among the least corrupt countries by Transparency International.
But unlike Norway their tax authorities don't post that information in a searchable online database. Also, they don't have a wealth tax, which in Norway provides snoopers with an insight into total worth.
An annual tax list has been available to the public in Norway since 1863. In 2001 it was published online, turning a paper curiosity into a powerful database. The transparency is supposed to uphold Scandinavian values of openness and egalitarianism, underpinning trust in one of the most expensive tax systems in the world.
But critics warn that having a fully searchable online directory of annual tax returns tramples privacy while appealing to voyeurism. "If the list was used as a way of finding out that people have not paid their share of tax then this would be a good thing. But I don't think it is used like that," said Rolf Lothe from the Norwegian Taxpayers' Association.
"Ninety-eight percent of people use it for entertainment, and historically children were being bullied in school over their parents' income." In 2013 the Norwegian government changed the rules to prevent anonymous searches, ensuring that if someone was checking out your tax affairs, you got an email to say who was doing the snooping.
"The intention was to reduce the public's search in the tax list merely out of curiosity, and thereby protect the privacy of the taxpayers," said Joergen Naesje, a Finance Ministry official. The law change worked: the number of searches dropped by 90 per cent. It also halted plans by developers to create apps allowing users to quickly find out the wealth of contacts on social networks or dating sites.